Senior Democrats have not responded well to Mr Trump's comments and have called on the FBI to investigate the Republican nominee's ties with the Russian government.

"For months, we have been asking the FBI to examine links between the Trump campaign and illegal Russian efforts to affect our election," read a joint statement from representatives Elijah Cummings, John Conyers, Elliot Engel and Bennie Thompson, NBC News reported.

"In light of this new evidence - and these exceptional circumstances - we call on the FBI to fully investigate and explain to the American people what steps it is taking to disrupt this ongoing criminal activity."